For example, conventional techniques in this field include that disclosed in an article "A Study on the Structure of PE-CVD SiOF Films" by Takashi Usami et al. on Shingaku Giho SDM 94-146 (November, 1994).
Silicon oxide films (SiO2) utilizing plasma enhanced chemical vapor deposition (PE-CVD) have been commonly used as insulation films of semiconductor devices. However, a trend toward finer and more highly integrated devices has resulted in increased capacitance between lines which has an influence on the driving power of the devices.
This has resulted in an increased need for insulation films having a lower relative dielectric constant, and fluoridated (F) silicon oxide films (SiOF) have come to attention as one of such materials having a low relative dielectric constant. As disclosed in the above-mentioned article, SiOF can be formed by mixing tetraethyl orthosilicate (TEOS), oxygen (O2), and an etching gas including fluorine (F) (e.g., C.sub.2 F.sub.6, CF.sub.4, NF.sub.3, HF, etc.) in a reaction chamber under plasma discharge.
However, an insulation film made of SiOF formed using the above-described conventional method has high absorptivity of moisture and absorbs a large amount of moisture thereinto.
This has resulted in problems including that:
(1) it can cause corrosion of a metal line which is a factor of a semiconductor device; and
(2) it reduces the lifetime of a transistor which forms a factor of a semiconductor device, and this has made it difficult to manufacture semiconductor devices of high reliability.
It is an object of the present invention to eliminate the above-described problems and to provide highly reliable semiconductor devices by reducing the absorptivity of moisture of insulation films made of SiOF.